<!DOCTYPE html>
<html>
<head>
	<title>Canvas测试</title>
	<meta charset="UTF-8">
	<script>
		//绘制饼图
		function drawCircle(canvasId, data_arr, color_arr, text_arr)
		{
			var c = document.getElementById(canvasId);
			var ctx = c.getContext("2d");

			var radius = c.height / 2 - 20; //半径
			var ox = radius + 20, oy = radius + 20; //圆心

			var width = 30, height = 10; //图例宽和高
			var posX = ox * 2 + 20, posY = 30;   //
			var textX = posX + width + 5, textY = posY + 10;

			var startAngle = 0; //起始弧度
			var endAngle = 0;   //结束弧度
			for (var i = 0; i < data_arr.length; i++)
			{
				//绘制饼图
				endAngle = endAngle + data_arr[i] * Math.PI * 2; //结束弧度
				ctx.fillStyle = color_arr[i];
				ctx.beginPath();
				ctx.moveTo(ox, oy); //移动到到圆心
				ctx.arc(ox, oy, radius, startAngle, endAngle, false);
				ctx.closePath();
				ctx.fill();
				startAngle = endAngle; //设置起始弧度

				//绘制比例图及文字
				ctx.fillStyle = color_arr[i];
				ctx.fillRect(posX, posY + 20 * i, width, height);
				ctx.moveTo(posX, posY + 20 * i);
				ctx.font = 'bold 12px 微软雅黑';    //斜体 30像素 微软雅黑字体
				ctx.fillStyle = color_arr[i]; //"#000000";
				var percent = text_arr[i] + "：" + 100 * data_arr[i] + "%";
				ctx.fillText(percent, textX, textY + 20 * i);
			}
		}

		function init() {
			//绘制饼图
			//比例数据和颜色
			var data_arr = [0.4146,0.27,0.2254,0.0874,0.026];
			var color_arr = ["#00FF21", "#FFAA00", "#00AABB", "#FF4400","#32CD32"];
			var text_arr = ["商圈", "美食街", "产业园区", "旅游景点","娱乐场所"];

			drawCircle("canvas_circle", data_arr, color_arr, text_arr);
		}

		//页面加载时执行init()函数
		window.onload = init;
	</script>
</head>
<body>
<h3>HTML5绘制饼图演示</h3>
<p>
	<canvas id="canvas_circle" width="500" height="300" style="border:2px solid #0026ff;" >
		浏览器不支持canvas
	</canvas>
</p>
</body>
</html>